1. Field of the Invention
The present invention relates generally, to a composition for a dielectric thin film, and specifically to a dielectric thin film comprising a metal oxide, and to a preparation method thereof. In particular, the present invention relates to a composition for a dielectric thin film, which is capable of being subjected to a low-temperature manufacturing process and which has a high dielectric constant (high-k). Also provided is a transistor device comprising the dielectric thin film, and an electronic device that in turn, comprises the transistor device, thereby exhibiting excellent electrical properties, such as, for example, a low operating voltage and a high charge mobility.
2. Description of the Related Art
In a flat display device, such as, for example, a liquid crystal display (“LCD”) or an electroluminescent display (ELD), thin film transistors (“TFT”) are used as switching devices for controlling the operation of pixels and as driving devices for driving the pixels. In addition, the application of TFTs to devices such as smart cards, or plastic chips for inventory tags, has also been considered.
The TFT comprises a gate insulating film consisting of a material having a high-k value. Such dielectric thin films having a high-k, are prepared through a vacuum deposition process, such as, for example, chemical vapor deposition (“CVD”) and atomic layer deposition (“ALD”), or through a solution process which uses a hydrolytic sol-gel technique. However, because the vacuum deposition process is conducted under high-temperature and high-vacuum conditions, it utilizes expensive equipment. Consequently, the cost of vacuum deposition is very high. Thus, alternative methods have been investigated for their ability to produce dielectric thin films with high-k values. For example, over the last several years solution processes, such as, for example, the low-cost hydrolytic sol-gel process, have received considerable attention.
The hydrolytic sol-gel process is a technique that is used for hydrolyzing a metal alkoxide or a metal salt in solution to thus produce a sol, which is subsequently gelled through condensation. The sol-gel process is conducted in three steps: hydrolysis, alcohol-producing condensation, and water-producing condensation. During the water-producing condensation step, an oxide having a hydroxyl group is converted into the final oxide. This conversion procedure is conducted at high temperatures of about 400 to about 500° C. This high-temperature process, which is performed at temperatures greater than or equal to 400° C., has the undesirable side-effect of causing deformation and damage to a typical substrate.